1. Field of the Invention
This invention relates to an imaging device to be incorporated in an endoscope or a microscope and, in particular to an imaging device which comprises an imaging section and means for compensating any displacement between the imaging section and an object of photography.
2. Description of the Related Art
In recent years, solid-state image sensors have been into made smaller and smaller. The miniaturized image sensors are built in imaging devices, which in turn are incorporated in endoscopes and microscopes. These devices convert the images of objects into electric signals. The electric signals are supplied to television receivers or the like, whereby the images of the objects are monitored. Further, the electronic still images the imaging devices have formed are recorded on recording media such as floppy disks or memory cards.
The imaging device incorporated in an endoscope or a microscope is operated in the following way, in order to record the image of an object. First, the operator places the device near the object, and turns on the power switch of the device, thereby to photograph the object. Then, while viewing the image formed by the device and displayed on a monitor screen, he or she moves the device until the imaging section picks up the image of the object. Further, he or she operates the device, thereby "freezing" the position of the imaging section. More specifically, the operator manipulates the positioning mechanism built in the device, thus moving the imaging section to a position which is desirable with respect to the object. After freezing the position of the imaging section, the operator pushes the record button of the device, whereby the image of the object, formed by the imaging section set at the desirable position, is recorded on a recording medium.
In the case where the imaging device is used in an endoscope, its imaging section is located within the distal end portion of the insertion section of the endoscope. The endoscope has a positioning mechanism which comprises an angle wire or the like and which is designed to move the distal end of the insertion section in a plane perpendicular to the optical axis of the imaging section and to set the distal end at a position desired with respect to an object existing in a body cavity. In some cases, the positioning mechanism is operated such that the imaging section gradually moves toward the object until it reaches the desired position.
As the imaging section is moved little by little, toward the desirable position of the object, it unavoidably vibrates. To make matters worse, the object is not always stationary, possibly moving, in which case the imaging section vibrates relative to the object. The image reconstructed from the electric signals supplied from the imaging section inevitably oscillates on the monitor screen so swiftly that the operator can hardly recognize the object correctly. Consequently, it is difficult for the operator to track the object by moving the distal end portion of the insertion section. If the operator pushes the record button while the image on the monitor screen is oscillating, the image recorded will be too unclear.